food’s journey through the.... types of digestion mechanical – physically breaking food down...
TRANSCRIPT
Food’s journey through the . . .
Types of Digestion Mechanical – physically
breaking food down into smaller pieces This creates more surface
area, so enzymes can get to more molecules
Chemical – use of chemicals and enzymes to break food into substances that can be absorbed
Mouth
Teeth are used for mechanical digestion to break the food into smaller pieces, so it can be easilyswallowed. Saliva contains enzymes used in
chemical digestion, which breaks down starches into simple sugars
The tongue is your strongest muscle used to manipulate food during mastication
Esophagus
The tube the food travels down to get to the stomach Peristalsis is the motion that pushes the
food down the tube. The tube pinches off above the food pushing it toward the stomach
You have an epiglottis that covers your esophagus while you are breathing and covers your trachea while you are swallowing
This prevents food from “going down the wrong tube”
Stomach
The stomach performs mechanical and chemical digestion of food. The stomach secretes a powerful acid
(pepsin) that breaks food down It also churns mixing the food with the acid
and breaking it down mechanically Chyme is the mixture of stomach acid
(pepsin), broken down food, and saliva that flows from the stomach into the small intestine
Duodenum
This is the first section of the small instestine, where most of the chemical digestion of carbohydrates, lipids, and proteins occurs
Chyme is joined with enzymes from the liver and pancreas that reduce acidity of the chyme and chemically digest the food
Small Intestine The small intestine are
covered in little finger like projections called villi
Villi increase the surface area of the small intestine to increase absorption of nutrients The usable nutrients are removed from the chyme and travel across the villi into the blood vessels that are inside it
Large Intestine
When the food arrives in the large intestine it is nutrient free The large intestine pulls any excess water
out of the remaining indigestible material creating feces
The large intestine is filled with bacteria that help our digestion process
When the large intestine is not removing enough water, diarrhea will result
When the large intestine removes too much water, constipation will occur
Rectum
The rectum will store the feces until there is enough to pass out of the
body When the rectum is full, you feel the urge to
go to the bathroom There is a sphincter muscle at the bottom of
the rectum called the anus This squeezes shut to keep feces in the
rectum and expands to allow it out when passing a stool
Liver, Pancreas, & Gallbladder The liver and pancreas secrete enzymes and digestive fluids that mix with the chyme in the duodenum The pancreas secretes a fluid to
neutralize the acidity of the stomach acid The liver secretes bile, which is used to break down fatty acids (lipids) Bile is stored in the gallbladder
Appendix
Is located near the junction of the small and large intestine The appendix is a vestigial organ,
which means it was once used but shrunk in size as it became less useful
Some organisms use the appendix to help break down cellulose in very fibrous substances (leaves)
Common Diseases
Diarrhea Constipation Appendicitis GERD IBS Ulcers Cirrhosis
What diseases or problems do you think of when you think of the digestive system?
Diverticulitis Ulcerative
Colitis Hemorrhoids Celiac’s Lactose
Intolerance Stomach Ache
Diarrhea and Constipation
Diarrhea – too much fluid in the bowel movements Caused by the large
intestine not removing enough water
Can be caused by viruses, bacteria, etc.
Can lead to dehydration and eventually death
Constipation – too much water being removed from the bowel movements Can be caused by
poor diet or not taking in enough water
Symptoms can be alleviated by taking laxatives
http://nature.ca/discover/exm/blddgstvsystm/index_e.cfm http://kitses.com/a
nimation/swfs/digestion.swf